Multiple pressure pump



* May 13, 1947.

E. L. BIVANS ET AL MULTIPLE PRESSURE PUMP Filed May 4, 1945 2Sheets-Sheet 1 .ln van-bar's Paul K. Been 2B1" J .F'nuJ {4. Mantqum EFL]wwma Patented May 13, 1947 MULTIPLE PRES SURE PUMP Elbert Litton Bivans,Los Angeles, Paul K. Beemer, Inglewood, and Paul H. Montgomery, LosAngeles, Calif., assignors to Preco Incorporated, a corporation ofCalifornia Application May 4, 1943, Serial No. 485,518

2 Claims. (01. 103-37) The present invention lies in the fleld of Pumpsand compressors, and it is particularly concerned with the provision ofa pump or compressor adapted to be selectively operated to producemultiple pressures or to pump diflering volumes of fluid. The particularembodiment which is hereinafter described in some detail has beendesigned with a view to specific use in connection with hydraulicpresses, but it will be understood that the invention is not necessarilylimited to such particular use, nor to operation upon liquids indistinction from other fluids. The specific illustrative embodimentwill, however, be described as for use in connection with a hydraulicpress, as typical but not limitative.

Hydraulic presses of various types and in various uses are commonlyoperated to move the plunger at relatively high velocity and with a lowoperating pressure until the plunger brings up against the work. Aftercontacting the work, the plunger is then operated by a smaller volume offluid at higher pressure. The present invention provides a simple formof pump mechanism which may be selectively and automatically operated todeliver either a large volume of fluid at relatively low pressure, or asmall volume of fluid at relatively high pressure.

The general nature of the invention will be most readily understoodafter consideration of the typical embodiments described in thefollowing specifications and illustrated in the accompanymg drawings inwhich Figs. 1 and 2 are vertical sections illustrating one form of pumpembodying the invention, Fig. 1 illustrating operation for delivery offluid at low pressure and Fig. 2 illustrating operation for delivery offluid at high pressure. I

Fig. 3 is a section illustrating the essential parts of a modified formof pump mechanism, illustrating its operation for delivery of fluid atlow pressure, 1

Fig. 4 is a similar view illustrating the operation of the pump of Fig.3 for delivery of fluid at high pressure, and

Figs. 5 and 6 are diagrammatic sections 11-- lustrating furthermodifications.

One of the characteristics of our pump resides in its use of two or moremovable fluid displace ment members of different eflective areas, bothacting upon the same pressure fluid. These displacement members may,within the scope of our invention, be of any suitable number, and of anysuitable types, such as for instance pistons, diaphragms or bellows. Inthe following described illustrative embodiment, the displacementmembers are shown as reciprocating plungers, and are shown as two innumber.

The movable displacement members are opermechanism under contro1 of theback pressures which are exerted on the displacement members. In oneform of the apparatus illustrated (Figs. 1 and 2) that selectiveoperation is semi-automatic, while in other forms (Figs. 3 to 6) theselective operation is wholly automatic.

We have mentioned the fact that, within the scope of the invention, thefluid displacement members may be of any suitable known type. They mayalso have any suitable physical relation to each other so long as theyboth act upon, and are reacted upon by, the same pressure fluids. In ourillustrative embodiments of the invention which utilize two displacementplungers, we prefer to adopt the simple arrangement of locating adiametrally smaller one of two displacement plungers within the largerone, in such a manner that the actuating mechanism, which is hereconnected to the smaller of the plungers, becomes the actuatingmechanism for both the plungers when both are operating to produce arelatively low pressure, and becomes the actuating mechanism for thesmaller plunger alone when it is operating to produce a relatively highpressure by reciprocation within a cylinder formed in the largerplunger.

Referring now more particularly to the form of pump shown in Figs. 1 and2, the main pump cylinder II) has a large plunger II which maypreferably be provided with a light spring l3 for urging it to itsoutermost position against a stop shoulder l2. Plunger II is the lowpressure plunger of relatively large area. The smaller highpressure'plunger l4 operates in cylinder bore 15 in the larger lowpressure plunger H.

In the form of apparatus shown in Figs. 1 and 2 an inwardl opening checkvalve It allows inflow of liquid through port l6 into cylinder l0 belowthe plungers; and an outwardly opening check valve I8 allows outwardflow of the pressure fluid from port [1, through output tube l9 to thepress or other apparatus where the pressure is used. Figs. 1 and 2indicate that the pump mechanism may be mounted in a fluid reservoir2|], from which fluid, such as oil,- is taken directly into inlet valveIt. In such a design, the element shown at 2| may be the plungercylinder of the hydraulic press to which the output tube i9 leads.'

II} the form of apparatus shown in Fig. 1, the

plunger l I.

outer end of high pressure plunger l4 isconnected by link 28 to anoscillatory arm 26 on an operat-.

'ing shaft 21, which shaft is here shown as being manually operatedthrough an oscillatory handle 28. The smaller plunger is shown as havinga shouldered head 28 at its upper end, this shouldered head seating onthe upper end of larger plunger II when the two plungers are in therelation to each other which is shown in F As will be understood whenthe following described mode of operation is considered, the uppershouldered end 01' smaller plunger .may be considered as a part of theoperating linkage or mechanism .ior the smaller plunger. .Consequentlyit may either be said that, in the relative positions 01' the plungersshown in Fig. 1, the operating mechanism of the smaller plunger hasoperating engagement with the larger plunger, or that the smallerplunger itself has such engagement with the larger plunger.

In operating at low pressure the two plungers maintain the relativepositions shown in Fig. 1.

That flgure shows the whole mechanism with the the manner just describedinvolves the application ot-a limited force to that plunger which isdirectly actuated; and the same operation may be obtained by mechanicalapplication of a limited force, acting through the full stroke distance.

Such an arrangement is illustrated diagrammatically in Fig. 5, where anoscillating arm 280 may It will be understood that return spring i8 ismerely a convenient means for moving larger plunger l I on its returnstroke. When the pump is operating upon substantially non-expansiveliquids there is no expansive pressure in the pump twoplungers at theupper or beginning end 01' the low pressure stroke. Downward movement ofoperating handle '28 from the position shown in full lines moves bothplungers to the lower ends of their strokes. 1 The effectivedisplacementarea is the aggregate area or thetwo plungers. A

. comparatively large volume or fluid, at relatively low pressure, isthus forced out of the pump cylinder ,to the hydraulic press, andcontinued reciprocation of handle 28 between the positions v shown infull and dotted lines in Fig. 1 will move the press plungercomparatively rapidly. 'As soon as the press plunger comes up againtsits work; greater pressure per unit area is necessary to move it. Thegreater reaction pressure against the large aggr ate area of the twoplungers is immediately felt by the operator, who then moves handle 28up to a higher position, as shown in Fig. 2, lifting the small highpressure plunger l4 to the relative position shown in that flgure. The

' larger plunger ll being now supported by the higher fluid pressurewhich is necessary to move the press plunger, the operator nowoscillates handle 28 and high pressure plunger ll between such an upperposition as shown in Fig. 2 and a lower P ition where head 28 comesagainst larger Continued reciprocation of the smaller high pressureplunger causes the pumping of a relatively small amount of pressurefluid at relatively higher pressure. The relations of volumes andpressures in the two selective opera-.- tions oi the pump will of coursebe determined by the relative areas and strokes of the two displacementplungers, and they may be designed to provide any relative pressures andvolumes which are desired.

In another mode of operation the stroke of smaller plunger l4 may alwaysstart from the uppermostposition shown in Fig.2. The first part of thedownward stroke will bring plunger I4 to the position, shown in Fig. l,and a small volume of fluid will have been displaced against whateverpressure exists at the time. If the fluid pressure is low enough thatthe force applied to handle 28 can move larger plunger I I down, thenthe stroke may go on through the downward movement of the largerplunger. Whenever the pressure builds unto the point where the appliedforce will, not move the larger plunger down below the position of Fig.1, then the stroke of the smaller plunger is automatically stopped intheposition of that figure. Manual operation in cylinder which can actreturn the larger plunger to the top of its stroke. If the pump beapplied to expansive fluids, the return spring is not necessary; butwhen applied to non-expansive fluids the spring 'iorms a simplesubstitute for a positive mechanical means of moving the largerdisplacement plunger on its return stroke. Figs. 3 and 4 illustrate theessentials of anothertypical pump design which is adapted to be entirelyautomatic in its operation, controlled solely by the reaction pressureson the fluids which are being pumped. In these flgures the physicaldesign is also somewhat dliierent from that shown in Figs. 1 and 2. Thecylinder body 85, containing cylinder 88, is closed at its lower end bya plug 81 which contains the valve controlled inlet port 88 and outletport 88, in which the check valves 48 and 4| are located.

The larger plunger 48 has shoulder 44 which brings up against a cylindershoulder 48 to limit the upward or outward stroke of the plunger.

- The'smaller plunger 46, reciprocating in cylinder bore 41 in thelarger plunger, is supported by a spring 48 with reference to the largerplunger. That spring 4'8 may be placed in any suitable physical positionrelative to the two plungers (for instance, in the design shown in Fig.1 such a spring might be placed between head 28 on the smaller plungerand upper end of the larger plunger) But in Figs. 3 and 4 spring 48 ispreferably shown as housed within larger plunger 48, with its lower endresting upon a suitable seat ring 48 in the larger plunger, and with thetoot of 'the smaller plunger 48 resting upon the upper end of thespring. Such an arrangement will cause the larger-plunger to be presseddownwardly by a force equal to the strength of spring 48, whenever thesmaller plunger is moved downwardly. And spring 48 is selected to be ofsuch strength as to transmit to the larger plunger a downward forcewhich is equal to the total low pressure on the larger plunger, plussuch incidental pressures as that which is exerted by the return spring50, and also plus the pressure necessary to overcome the inertia forcesof the parts of the system moved by spring 48. At low operating speedsthis last item may be negligible; at high speeds it is taken intoaccount.

Return spring 58 is here shown as conveniently bearing at its upper endagainst the same seat ring 48 which roots the spring 48. In effecthowever spring 58 exerts itsupward pressure against larger plunger 43 tomove that plunger upwardly on its return stroke, because spring 48 isconsiderably stronger than spring 50.

The design shown in Figs. 3 and 4 may be operated manually by such anoperating mechanism as shown in Figs, 1 and 2. Figs. 3 and 4 show anoperating mechanism which may either be manually driven or power driven.As shown in those figures an eccentric ring 55 is provided on anoperating shaft 56. The operating shaft 56 may either be oscillated orcontinuously rotated, manually or by power. The eccentric ring 55 maybear directly upon the upper end of small plunger 48.

Fig, 3 shows the relative positions of the parts at the upper end ofeach stroke. If the fluid pressure in cylinder 36 is below that forwhich spring 48 is selected, the two plungers will move down as a, unit,to expel a full volume of fluid at relatively low pressure: andreciprocation of the two plungers will continue as long as the fluidpressure is below that which corresponds to the strength of spring 48.However, as soon as the fluid pressure for any reason rises above thespecified pressure, then the fluid pressure will hold larger plunger 43at the upper end of its stroke, while smaller plunger 46 moves downwardto the relative position shown in Fig. 4, compressing spring 48.Continued operation will then reciprocate smaller plunger 46 between therelative positions shown in Figs, 4 and 3, with the effect of pumpingout a relatively small volume of fluid at the desired relative highpressure. Operation in the high pressure range, continuously compressingand expanding spring 48 does not cause waste of power as the spring uponrelease returns substantially all its energy of compression to thesystem.

We have said that spring 50 may be inserted at any suitable place in thedrive for the larger or secondary plunger; ior instance, between thatplunger and the driving elements of the smaller or primary plunger. Fig.6 shows such an arrangement diagrammatically, where the spring 50a isinserted between plunger II and head 29a of plunger Hi. This arrangementhas been spoken of before as the equivalent of spring 48 of Figs. 3 and4. In any of the arrangements which have been described, the secondarilydriven displacement member (the larger plunger here) can be said to bedriven from the drive of the primarily driven member (the smallerplunger here) although in some cases (e. g., Figs, 3 and 4) the drive isspecifically through the primarily driven displacement member.

Some general remarks in final summary may be helpful to an understandingof the invention typified by the described embodiments. Broadlyspeaking, the two plungers may be regarded as two movable fluiddisplacement members, one primarily driven and the other secondarilydriven from the primary displacement member or from its drive means. Inthe form of Figs. 1 and 2 the selective action which determines whetheror not the secondary member is driven, or whether the primary memberalone is driven, depends either upon volitional change of stroke of theprimary driving means, or upon the fact that a limited force (forinstance, manual) is applied to the primary drive and that the stroke ofthat drive and of the primary displacement member is automaticallychanged when the back pressure against the secondary member exceeds theapplied force. In these forms of the pump the pressures per unit areawhich can be raised (assuming a limited force to be applied) dependentirely on the displacement areas oi' the displacement members.

In the form illustrated in Fig. 5 the selective action is also automatic.in the same manner as mentioned just above, the limitation of applieddriving force in the primary drive being supplied by'spring 30. The sameobservations apply to this form as to the limited-force mode oroperation mentioned Just above.

In the forms illustrated in Figs. 3, 4 and 6 the stroke of the primarydrive and primary displacement member is not changed. The automaticselective action in these forms of the pump depends upon the fact thatthe drive of the secondary displacement member-from the primaryunit-includes a limited force transmitting element (spring 50 or 50a).In these forms. the unit pressure which can be raised by the secondarydisplacement member is determined by the total displacement area and thestrength of the force transmitting element, regardless of how much poweror force may be initially applied to the drive. But the unit pressurewhich can be raised by the primary displacement member is limited onlyby the amount or Iorce which is applied to it; the two pressures are notnecessarily in a ratio determined by the areas of the displacementmembers.

The area ratios of the two displacement members need no be unequal, andthe area of the primary member need not be smaller than that of thesecondary; with any ratio the volumetric displacement of the two memberstogether is of course greater than that of the primary alone, and onlyfor volumetric ratios greater than two to one will the displacement areaof the primary member be less than that of the secondary.

We use the terms primary and secondary, as applied to the displacementmembers, in the sense that the primary member is the one which isdirectly driven and the secondary is the one which is selectively drivenwith the primary.

We claim:

1. In pumps of the type which include primary and secondary reciprocablefluid displacement members each exposed to and acting upon the samepressure fluid between inlet and outlet valves and having inward fluiddisplacement strokes and outward fluid induction strokes, the primarymember being reciprocable independently of the secondary; a selectiveoperating system for the displacement members which includes, a fixedstop which forms a terminal limit to the outward stroke of the secondarymember and defines a position from which that member starts its inwardstroke, a spring acting on the secondary member tending to move itoutward to a position against the limit stop, the secondary member beingalso held against the limit stop by the fluid pressure on that member,and driving mechanism for the two members including, means forreciprocating the primary member through either of two spatiallyseparated reciprocative move-- ments. and a shoulder associated with theprimary reciprocating means and adapted to drivingly engage thesecondary member on inward movement only of the primary member topositively drive the secondary member inwardly, the primary member beingotherwise free of connection with the secondary member and adapted to bereciprocated independently thereof, and the secondary member being atall times free to move inwardly from its outer stopped positionexcepting only for the spring pressure and the fluid pressure on it.

7 V 2. A selective operating system as specified claim 1, and in whichthe primary reciprocating means includes a yielding element adapted t 7fmg under a predetermined pressure drivinz the 1862823 primary memberinwardly. 5 zgjogo ELBERT m'rroN'BIvANs. 3222:: PAUL K. IBEEMER.1829'451 PAUL H. MONTGOMERY. 10 5 REFERENCES CITED The followingreferences are or record in the N m r tile 01" this patent:

8 UNITED sum mum's Name I Date Baker Mar. 3, 1031 Holveck June 14, 1982Lindsay May 1, 1860 Stucky Oct. 15, 1878 McNab Nov. 11, 1930 I McNabOct. 27. 19:41 Ten Eyck Mar. 1, 1901 FOREIGN PATENTS Country Date GreatBritain 1885

